Spirally formed pipe or tube is typically formed from a single strip of metal. As a pipe is formed, the strip of metal is coiled and adjacent edges of the strips are folded and pressed together to form a lockseam. When the spirally formed pipe reaches a desired length, a pipe cutting device severs the pipe. Spiral pipe has applications in many areas, including vehicle oil filters, culvert pipe and HVAC (heating, ventilation and air-conditioning).
Conventional pipe cutters often utilize saw blades or cutting knives. Saw blades may present safety issues as well as problems with forming clean cuts on the pipe. Pipe cutting knives may be advantageous depending on the nature of the pipe that is formed.
When spiral pipe is formed, a strip of material is coiled in the pipe former so that the adjacent edges of the coiled strip overlap. In some pipe formers, a pair of clinching rollers are used together to fold the adjacent edges of the coiled strip onto each other and to compress the folded edges into a helical lockseam. This lockseam may consist of four layers of material, for example.
A design challenge for pipe cutters lies in preventing problems with the formation of the pipe. Typically, the cutting blades or knives in a conventional pipe cutter will be configured in a fixed arrangement or in one that is free to rotate, that is, passively rotate. Material may encounter resistance when presented to such fixed or passive cutting arrangements. The helical lockseam in particular may create difficulties for fixed or passively rotatable knives. In the case of a thin gauge or a light material, the material can buckle when it encounters the fixed or passively rotatable knife. A thick gauge or a heavy material, will in general create a thicker lockseam. The lockseam might cause the machine to stall when it encounters the knife. It would be desirable to implement an arrangement that assists the cut to decrease the likelihood of common pipe formation mishaps such as buckling of light material and as stalling of the machine during the processing of heavy material.